The bone pile at the Moss Landing, Calif., whaling shore station, photographed 1919.Courtesy San Francisco Maritime Museum Association.
The bone pile at the Moss Landing, Calif., whaling shore station, photographed 1919.Courtesy San Francisco Maritime Museum Association.
Already the Russians have expressed proprietary interest because they control the summer feeding grounds. Likewise, with the same reasoning, the Mexicans control the breeding waters. It would appear that the American interests, limited to two small shore stations at San Francisco, must be content to secure those whales which will escape the efficient Russian and Japanese fleets which could, at the most opportune moment, secure the species before the beginning of the long migration. At any rate, the species can only serve as an extra species in areas where whaling is already marginal because of limited stocks. It is hoped that eventually the whaling interest will remove the gray whale from whaling, leaving it as a living memorial to whaling.
Conservationists should remember that nature has wisely designed each species of plant and animal with a built-in margin of safety; namely, a surplus of young which will repopulate the species from periods of extreme adversity. Yet these surpluses must somehow usually be eliminated lest the species overpopulate its habitat and destroy its own sustenance. The controls which limit the population are many and the population existing from year to year is the statistical average of these many controls. Diseases, predators, and other adversities are necessary evils, which are in the final analysis blessings in disguise. Whales, too, have their checks, although we are a long way from knowing their relative importance.
Perhaps the most critical moment in the life of the whale is birth, because the newborn whale must surface immediately or suffocate. Any abnormality in the birth process or weakness on the part of the infant may cause its loss. Inasmuch as a whale calves only every other year, the loss of a baby is serious, and especially so because a whale produces but a single calf. Less than one per cent of whale births are twins which is about the same frequency as for humans. A careful examination of the shores around the breeding lagoons reveals that a few babies are lost at birth.
Life expectancy is another very useful statistic for population studies. The whaling industry has no easy way of finding this out because whaling never gives an individual whale the chance to attain old age. Perhaps we can eventually determine life expectancy for the gray whale if it can continue to be protected from whaling. By counting the number of babies produced each year, and knowing the life expectancy, We might indirectly obtain the number of whales which die before they have realized their life expectancy. This number should represent the surplus on which whaling could be based. A further study would be necessary to determine what percentage of the surplus could be diverted to the whaling industry.
The problem of aging whales is an important one, and one to which much thought has been given. Actually, it is desirable to know at what age sexual maturity occurs; at what age physical maturity; at what age reproduction is no longer possible, and lastly, the age at death. In addition, we need to know the gestation period and the average number of pregnancies of which the female is capable. Many of these statistics can be obtained from the examination of a freshly killed whale. Such age determinations are made on every specimen which comes aboard the factory ships and also at the shore stations. There is some doubt as to the accuracy of some of these. Physical maturity is delayed in whales for many years, and it is judged complete when the cartilaginous end plates fuse to each vertebrum (backbone). After fusion, further lineal growth is impossible and after this time whales have been noted to shrink slightly each year.
The other structures which a biologist collects for aging are the ovaries of the female whale. These are sliced across into half-inch slabs, and the number of exposed grayish masses are counted. There is one of these structures produced for each pregnancy, and they persist as scar tissue throughout the life of the whale. These structures are functional during pregnancy and nursing and are responsible for a successful pregnancy. A count of these gives the investigator the total number of offspring which have been produced. If one assumes that the whale has not missed an opportunityto produce a baby, the count of these gives the age, assuming one knows the age of sexual maturity and the maximum length of bearing.
In recent years other structures have been tried for aging, so that males might also be aged, as well as females past the reproductive period. The best structure is the cylinder of wax which fills the outer canal of the ear leading to the eardrum. This enlarges as the whale grows, and the growth is marked by banding very similar in appearance to tree rings. Slicing the plug, the rings can be exposed and counted. There are produced but two rings a year. Toothed whales can be aged by sawing the teeth in half and noting the banding. Baleen also is periodically enlarged, but this is more difficult to check.
The whaling industry spends a few weeks before the whaling season and at the end, hunting whales with a much lighter gun which implants a numbered cylinder deep in the skin of the whale. Each whale so marked is logged as to the species and the latitude and the longitude, and lastly, the date. Should the marked whale be processed in any succeeding season, a second entry is completed giving the date and place of capture. These records are used to determine the migration routes and the degree of intermingling of adjacent populations. The ratio of marked whales to unmarked whales allows the estimation of the probable size of the whale population. The length of time elapsing until a marked whale is recovered is an indication of the intensity of whaling.
Unlike the situation in the fishing industry where the reproductive potential of the fish is more than adequate to repopulate quickly, in the whaling industry the reproductive potential is small. Only one-fourth of the population can contribute replacements each year, and then only a single baby. Of course, each offspring has a reasonable chance of reaching maturity, whereas with fish only a very small number achieve adulthood.
One might expect that whales would be less affected by the fluctuations in environmental conditions, but this is only a surmise. We do not know as yet how to ascertain whether the food of whales is ever inadequate. Certainly the fact that baleen whales do best around the polar seas suggests that climatic fluctuations of the magnitude and duration of those producing the ice ages, may have profound effects on them.
We can only hope that man will learn to exploit whales in such a way as to take only the surplus and leave the main stock, creating thereby a perpetual resource. Man can best profit esthetically and scientifically by leaving the gray whale free of whaling as a control population.
Gray whale making a deep dive.Photograph by T. J. Walker.
Gray whale making a deep dive.Photograph by T. J. Walker.
Gray whale spouting.Courtesy Scripps Institute of Oceanography.
Gray whale spouting.Courtesy Scripps Institute of Oceanography.
Scientific names of all North American cetaceans with common names most in use. Maximum size indicated.
Region: (A) Atlantic Ocean, (P) Pacific Ocean, (C) Circumpolar